1. Field of the Invention
The present invention generally relates to a processor that executes programs, and more particularly, to a processor that can be employed in an image processing apparatus such as a printer, a copying machine, or a combination printing, copying, and facsimile machine. The present invention also relates to control operations performed when an image processing device shifts from a power saving mode to a normal operation mode.
2. Description of the Related Art
In recent years, various techniques have been employed to reduce power consumptions in image processing apparatuses which are, for example, facsimile machines, printers, and copying machines. There have been not only techniques of reducing the power consumptions of print engines, but also a technique of lowering or completely stopping the clock frequency of a circuit such as an ASIC (Application Specific Integrated Circuit), and a technique of cutting off power supply to parts such as an image memory and the ASIC that are not required to operate in a power saving mode.
Besides, it is known that an attempt to speed up data processing when an image processing apparatus such as a facsimile machine, a printer and a copying machine shifts from a power saving mode to a normal operation mode. One of the most common techniques is a method in which a program is copied from a ROM (Read Only Memory) that requires a long access time into a RAM (Random Access Memory) that requires a short access time, so that the CPU in the controller reads the program from the RAM to perform a high-speed operation.
However, the amount of data to be written in a ROM has been rapidly increasing in recent years, and the program copying from a ROM to a RAM is too time-consuming in accordance with the above method in which a program is copied from the ROM into the RAM, and the CPU reads the program from the RAM. Therefore, it is difficult to shorten the time required to return to the normal operation mode.
In an image processing apparatus such as a printer or a copying machine, the control panel does not indicate any message while a program is being copied from the ROM into the RAM, even when the power switch is on. This may cause inconvenience to each user of the apparatus.